The invention is related to the field of speech processing, and in particular to a speech processing system utilizing speech production components, speech analysis components, noise generators, and computing differences in signal attributes, and controlling speech production arranged in a feedback configuration.
FIG. 1 is a schematic diagram highlighting the major regions of the vocal tract 2 involved in speech production, namely, nasal cavity, oral cavity, pharynx, larynx, trachea, bronchi and lungs. FIG. 2 shows a detailed cross-section of the speech production system 4 illustrating the three main components namely, the glottis within the larynx, the subglottal system and the supraglottal vocal tract. A structure called the soft palate (velum) separates the oral and nasal cavities. The lungs and respiratory muscles provide the vocal power supply. Voiced speech is produced by air expelled from the lungs causing the vocal folds to vibrate as a relaxation oscillator. The ejected air stream flow in pulses and is modulated by the vocal tract. In unvoiced speech, sounds are created by passing the stream of air through a narrow constriction in the tract. They can also arise by making a complete closure, building up pressure behind it, and then followed by an abrupt release. In the first case, a turbulent flow is produced while in the second case, a brief transient excitation occurs. The puffs of air are shaped into sound waves of speech and eventually, radiated from the lips and/or nose.
The invention provides an approach in modeling speech synthesis techniques with an analog vocal tract.